Traditionally, Gaussian or flat-top beams are used to melt solid material in laser cladding process (applicable in 3D printing field) or welding. Although they can melt solid material quickly, the energy at the center point of the Gaussian spot is highly concentrated, sometimes resulting in overheating and causing vaporization to occur. The vaporized molecules, when leaving the surface, will cause a recoil pressure that pushes the molten pool, which often causes splashing of the material and depressions formed on the surface. Also, as the energy of the center point of the Gaussian beam is higher, the shape of the weld beads appears oval-like. This give rise to higher overlapping rates between the molten areas in the laser cladding process or the weld beads, sometimes even as high as 50%. Therefore, the production rate of the process is relatively low.
Therefore, there is an urgent need in this field to design a device for heating to generate a uniform molten pool that, in particular, eliminates vaporization of the material, creates uniform weld beads and reduces the overlapping rate of the weld beads or the molten areas in the laser cladding process.